Currently, Evolved UTRA and UTRAN are under study as a next generation mobile telephone system in the ahead of 3GPP (3rd Generation Partnership Project), where UTRA and UTRAN stand for UMTS Terrestrial Radio Access and UMTS Terrestrial Radio Access Network, respectively, and UMTS stands for Universal Mobile Telecommunications System. According to Evolved UTRA and UTRAN, wireless base station apparatuses and gateway apparatuses are connected through an IP (Internet Protocol) network. In the case where Ethernet is used for establishing physical links which realize the connections through the IP network, the MAC address resolution is performed by using ARP (Address Resolution Protocol).
In the case where MAC address resolution is performed by use of ARP, IP packets are temporarily buffered before being transmitted. Therefore, the MAC address resolution by use of ARP can cause loss or delay in transmission of IP packets.
In the W-CDMA (Wideband Code Division Multiple Access) mobile telephone system, which is one of the conventional wireless communication systems, the main data-plane traffic is non-real time traffic even Ethernet is used in the IP network. Therefore, it is possible to consider that the data-plane traffic is not significantly affected by the MAC address resolution by use of ARP. However, the real-time traffic of streaming of voice, large-capacity movie, or the like is greatly affected by the MAC address resolution by use of ARP.
Consider the case where the MAC address, for a call, of a call connection device or a router in an IP route in the data plane is unlearned immediately after call connection in the control plane. In such a case, an operation for learning a MAC address is performed in each node before user traffic in the data plane is started. Specifically, MAC address resolution by use of ARP is performed when the user traffic in the data plane is started.
Since buffering of IP packets occurs in the user traffic through each node, loss or delay in transmission of packets occur in the user traffic.
Further, in the case where an L2 switch has not learned of the MAC addresses in a route for a call although routers in the route have already learned of the MAC addresses, the L2 switch performs flooding, in which IP packets are transmitted through all ports except reception ports. Therefore, network resources which are irrelevant to the call are consumed, i.e., loss of network resources occurs.
A known call-connection terminating device acquires a next-hop IP address corresponding to the IP address in the current hop, and performs ARP resolution for the next-hop IP address in advance. (See, for example, Japanese Laid-open Patent Publication No. 2006-211545.)
However, the technique disclosed in Japanese Laid-open Patent Publication No. 2006-211545 may not able to be applied to communication systems using a control plane and a data plane in which different IP routes can be arranged. Such communication systems include the mobile communication systems for mobile telephone using the W-CDMA or other protocols, the IP telephone systems using SIP (Session Initiation Protocol), MEGP (MEdia Gateway Control Protocol), or the like, and the real-time communication systems in accordance with H.323.